For the sake of argument:

Relayed Bosch 005 fuel pump, Bosch Green-top injectors...

What FPR, and set to what pressure? This would be with off-the-shelf MRC software meant for RS2 turbo and green-tops.

Your fuel pressure is going to need to be less then 4 BAR. The exact number hard to say especially without a Wideband O2 sensor to get your WOT A/F ratios. Has anyone seen a fuel pressure drop with the stock fuel pump at RS2 levels?

If it's written for 3.8 Bar then the injector duty cycle will be slightly higher than with a 4.0 Bar differential across the injector.

I was running a rs2 fpr with an agressive tune and it was not fun :) then bumped it to a 5bar custom garage tuned hahahaha bumped duty right up to 88% haaaaaaaaaaaaaaaaaahahahaha

...or on the list.

While it would be nice to have a custom tune, I don't have that sort of access.

If there is a specific FPR for RS2 applications, then I need to make sure I get it. I was going to ask Bob Myers, but I'll ask you - since you're essentially running the set-up I'm going to run - what FPR are you using?

(And what fuel pump - I'm guessing that makes a difference for total flow.)

Looks like I'll be talkin' to Bob about this stuff.

From my experiance moving from the Stock pump to a 044 "definitly" requires a remap of the ECU. I would suspect that only 2.9 PSI is NOT going to be the difference. You WILL be richer with the 005 fuel pump. And a 3.8 BAR and 4.0 BAR fpr is not going to make up for it.

Plain and simple..if you upgrade..get an adjustable FPR at min. But highly recommend a Wideband A/F gauge. IS the richness going to be severe..no..is it going to impact peak performance..yes.

Or does it expect the pressure to drop off at high RPM at WOT?

If the software you are running expects a stock pump that can't supply enough fuel to get 4 bar at the injector and the software is tuned to compensate for this lack of pressure by increasing injector duty cycle then upgrading to a higher flow pump will make the engine run richer.

However, if you have a fuel pump that is supplying 4 bar to the injector under all conditions and the software always expects to have 4 bar, it doesn't matter if you upgrade pumps because you will still be limited to a max pressure of 4 bar by the FPR.

22 PSI in your boost..add 4 BAR to that number go get expected fuel rail pressure. The issue with small fuel pumps is they loose fuel pressure as the boost increases. Larger pumps can maintain expected pressure. Now if you are RS2 or below..you are fine especially with Relay mod. Beyond that...fuel pressure will drop at WOT...I have video of that ;)

software because our air is much denser than Denver's and the fuel pump has a tougher time keeping up (to achieve a non-lean A/F ratio).